The words prayers, preyers sound the same but have different meanings and spellings. Why do prayers, preyers sound the same even though they are completely different words?
The answer is simple: prayers, preyers are homophones of the English language.
Plural form of prayer.
Plural form of preyer.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.